The student is accurate in that the process is inefficient; many amino acids, carbohydrates and other materials useful to the cell are “wasted” by excretion. However, the excreted materials contain digestive enzymes that have destroyed the engulfed organisms and that could also degrade molecules inside the cell if released. To prevent this damaging effect, the enzyme must be excreted from the cell. Moreover, if the engulfed microorganisms produced a toxin, this material may not be destroyed by the digestive enzymes and should not be released inside the cell.